<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link rel="stylesheet" href="./styles/index.css" />
  <title>Document</title>
</head>

<body>
  <div id="app" class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody>
          <tr v-for="(item,index) in list" :key="item.id">
            <td v-html="index+1"></td>
            <td v-html="item.subject"></td>
            <td v-html="item.score" :class="{red:item.score &lt; 60}"></td>
            <td><a href="#" @click="list.splice(index,1)">删除</a></td>
          </tr>
        </tbody>
        <tbody>
          <tr>
            <td colspan="5" v-show="list.length<=0">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>

        <tfoot>
          <tr>
            <td colspan="5">
              <span>总分：{{sum}}</span>
              <span style="margin-left: 50px">平均分：{{divce}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" placeholder="请输入科目" v-model.trim="subject" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input @keyup.enter="addpro(subject, score)" type="text" placeholder="请输入分数" v-model.number="score" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit" @click="addpro(subject, score)">添加</button>
        </div>
      </div>
    </div>
  </div>
  <script src="../../vue/vue.js"></script>

  <script>
    const app = new Vue({
      el: '#app',
      data: {
        list: [
          // { id: 1, subject: '语文', score: 20 },
          // { id: 7, subject: '数学', score: 99 },
          // { id: 12, subject: '英语', score: 70 },
        ],
        subject: '',
        score: ''
      },
      methods: {
        addpro(subject, score) {

          console.log(subject, score);
          if (!subject) {
            alert('科目不能为空');
            return
          }
          // 判断是否为数字 也能判断是否为空
          if (typeof this.score !== 'number') {
            alert('分数要为数字|分数不能为空');
            return
          }

          this.list.unshift({ subject, score })
          this.subject = '';
          this.score = ''
        }
      }
      ,
      computed: {
        sum: {
          get() {
            return this.list.reduce((all, next) => all + next.score, 0);
          }
        },
        divce() {
          return this.list.length === 0 ? 0 : (this.sum / this.list.length).toFixed(2);
        }
      }
    })
  </script>
</body>

</html>